WHEN THE Ravens were traveling to Gillette Stadium a year ago to challenge the Patriots for the AFC championship, Corey Graham was instead headed for Hawaii on behalf of the Chicago Bears, a berth in the Pro Bowl his reward for his special teams brilliance. But the Baltimore defensive back is nonetheless well aware of the environment he'll encounter when his new team visits New England Sunday seeking to simultaneously avenge last January's loss and secure the AFC's spot in Super Bowl XLVII.

"All of my roommates were big-time New England Patriot fans in college, and all of my friends still to this day are diehard Patriots fans and Red Sox fans," the University of New Hampshire product said this week. "It is a big game for me, obviously. I went to college in that area. I was up there all of the time. I know what it is like. They have die-hard fans out there."

And Sunday evening the former Wildcat standout figures to be a factor if New England's dreams of New Orleans do, indeed, die hard on the FieldTurf of Foxborough.

No longer pigeonholed as a special teams ace the way he was in Chicago, Graham signed with Baltimore last spring with hopes of getting more opportunities on defense - and since injuries helped those opportunities present themselves, he has become a force not only responsible for the Ravens getting this far, but maybe also for how much farther they will go.

Last week in Denver he returned a first-quarter interception for a touchdown, then picked off Peyton Manning again in overtime to set up the field goal that allowed Baltimore to advance. And now he faces an even more difficult and important challenge, charged with taking away Tom Brady's favorite target and trying to cover Wes Welker in the slot.

It's not an easy task, as Welker's 118 regular-season catches and 131 divisional-round receiving yards would suggest. But it's a task the Ravens are confident he's got the ability to handle.

"Corey is just a great football player, and that's the thing," said Baltimore Coach John Harbaugh, who didn't overlook Graham's defensive skills the way Lovie Smith's staff had with the Bears. "When you see guys play well on tape, whatever they're doing, if they do it well, you've got a football player. So, we started with that.

"He's got very good ball skills. He's got very good feet. He's got tremendous understanding of the game. He understands the coverages and things like that. Good body control. So, he's got all the things that make for a good defensive back."

Welker burned Baltimore for eight catches and 142 yards when the teams met in September, but that was before Lardarius Webb was lost for the season with a knee injury and Jimmy Smith missed a month with a sports hernia. The first week Smith was inactive, Graham delivered eight tackles, defended three passes and had an interception in a win over Pittsburgh, then two weeks later he followed it up with another pick and 11 tackles against those same Steelers.

All together his impact over the past nine games is quantified by 60 tackles, half a sack, four interceptions and 13 passes defensed - though today his impact may not be measurable in his own numbers as much as Welker's.

Last week's win over Houston provided yet another example that, especially without tight end Rob Gronkowski, Welker is who Brady looks to both in big moments and in order to keep things moving in an efficient and effective rhythm. So If Graham can limit Welker with minimal help, it would be an enormous boost for the league's 17th-ranked pass defense, because it can then pledge any extra bodies to protecting against Brady's other weapons or perhaps putting pressure on the quarterback.

But if Graham can't singly contain Welker in the slot, and Baltimore needs to bracket or even double him, it likely leaves the Ravens exploitable elsewhere against the NFL's fourth-best passing attack.

Given how good the Pats are when Brady is clicking, that puts the ex-Wildcat's performance at the crux of crowning the AFC champion.

"I have my hands full in the slot," Graham said, "but I am up to the challenge."

And his old friends from Durham know enough to believe that. Even if their buddy might be the one standing in the way of their team.

"All of my friends are going to be out there, probably, with Patriot jerseys on," Graham said. "It's going to be a little different his week, but no matter who you are playing, you want to go out there and win. This is for all of the marbles, to get to the Super Bowl, so this is ever bigger."

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UNDERRATED: Paul Kruger. For all the talk of Ray Lewis, Ed Reed, Terrell Suggs and Haloti Ngata, guys like Graham and Kruger have been the playmakers for the Ravens this postseason. Kruger has 10 sacks in his past 10 games, including 2.5 in the wild-card round, and is someone the Patriots need to account for coming off the edge.

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OVERRATED: Patriots' third down struggles. New England allowed opponents to convert on 40 percent of third-down chances during the regular season, though that number doesn't reflect how much they improved over the year. From Thanksgiving on, the Pats allowed conversions on only 29.8 percent of enemy opportunities.

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KEY MATCHUP: Patriots vs. the deep ball. The Ravens' season famously lived by the deep ball last week. And that wasn't an exception, especially since Jim Caldwell assumed play-calling duties. In Baltimore's three wins under its new offensive coordinator, its 10 biggest plays of each game have accounted for 64 percent of their total offense. Joe Flacco is overall averaging 9.9 yards per pass attempt in that span, but remove those big throws and the number slides to 2.9. Expect a lot of deep shots today - especially against a Pats defense that allowed a league-worst 74 completions of at least 20 yards.

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KEEP AN EYE ON: Aqib Talib's positioning. Since his arrival, the cornerback has typically followed the opponent's top receiver, though Talib's optimal use today may mean staying on the right side of the Ravens' formation, as Flacco's rating is 115.9 this season on passes to that direction, 83.9 to the left - and just 68.3 on throws to the left sideline.

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STAT OF THE WEEK: Including passes and runs, this postseason the Ravens have 14 plays of 20-plus yards, totaling 510 yards. Their other 116 plays have totaled 408 yards.

Dave D'Onofrio covers the Patriots for the New Hampshire Union Leader and Sunday News. His e-mail address is ddonof13@gmail.com.